Diodes Incorporated AH5771-PG-B

Overview

AH5771-PG-B from Diodes Incorporated is a single-phase Hall-effect latch smart fan motor controller IC integrating Hall sensor, amplifier, comparator with hysteresis, and full-bridge driver in SIP-4L package. It operates from 2.5V to 15V supply, delivers up to 400mA peak output current, features rotor lock detection with automatic self-restart, and supports brushless DC fan commutation in compact cooling modules.

For engineers reviewing the AH5771-PG-B datasheet, AH5771-PG-B pinout, AH5771-PG-B application, or AH5771-PG-B equivalent, key selection criteria include its integrated Hall sensing path, lock-protection logic, 220ms typical on-time at 12V, low-voltage startup capability (2.5V), and SIP-4L thermal derating profile across –40°C to +100°C.

Technical Context

The AH5771-PG-B implements a closed-loop commutation architecture where the internal Hall sensor detects rotor position, the error amplifier conditions the magnetic signal, and the comparator with 60G hysteresis rejects noise before triggering the full-bridge driver. The bandgap-regulated bias ensures stable operation across voltage and temperature.

Its rotor lock protection monitors stalled rotation via timing violation detection and initiates automatic restart after a defined recovery interval-eliminating need for external watchdog circuitry. No external timing capacitor is required, as on-time (220ms typ.) and duty ratio (10% typ.) are internally fixed.

Key Specifications

Pinout & Package

SIP-4L (Single In-line Package, 4-lead) with gull-wing leads, 1.95mm lead pitch, 0.7mm active area depth, and green molding compound compliant with RoHS Directive 2002/95/EC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-phase BLDC fan controller applications.

Compared with A3967SLBTR-T and NCV7703BDR2G, the AH5771-PG-B offers lowest BOM count and fastest time-to-operation for fixed-speed, self-protecting single-phase fans-but trades off programmability and multi-phase scalability.

Availability

AH5771-PG-B is available at Aetrix Electronics and suitable for server cooling, industrial cabinet ventilation, automotive HVAC blowers, and medical diagnostic equipment requiring stable component supply and long-term obsolescence management.

Supply support for AH5771-PG-B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design centers across Asia and manufacturing in China, Taiwan, and Malaysia.

The AH5771 belongs to Diodes' Smart Motor Control product line, engineered specifically for cost-sensitive, high-volume BLDC fan applications where integration, reliability, and thermal resilience are prioritized over programmability.

FAQ

What is the minimum supply voltage required for AH5771-PG-B to start commutation?

The AH5771-PG-B guarantees functional startup at Vdd = 2.5V, verified across –40°C to +100°C. Below this threshold, Hall sensor bias and comparator thresholds become unstable, causing erratic or failed commutation. Operation below 2.5V is not characterized and may result in undefined behavior or latch-up.

Does AH5771-PG-B require an external reverse-protection diode?

Yes-D1 (reverse diode) is mandatory per the recommended application circuit. The device lacks internal reverse-voltage protection; applying –0.3V or lower to Vdd relative to VSS will damage the internal regulator and Hall sensor. A Schottky diode (e.g., 1N5819) placed in series with Vdd is standard practice.

Can AH5771-PG-B drive a fan rated above 1W?

No-its 400mA peak output current and 550mW power dissipation limit safe continuous operation to ~1W loads at 12V. Driving higher-power fans risks thermal shutdown or permanent damage. For >1W applications, use external half-bridge drivers controlled by AH5771's logic outputs (not supported-O1/O2 are power outputs only).

How does rotor lock detection work without external components?

The AH5771-PG-B monitors Hall signal timing: if no valid magnetic transition occurs within 2× the nominal on-time (≈440ms), it triggers lock detection, disables outputs, and initiates a 2-second restart delay before attempting commutation again-fully implemented in analog/digital logic without external timers or microcontrollers.